1. Technical Field of the Invention
The present invention relates to a method and an apparatus for removing radioactive cesium from waste containing radioactive cesium and effectively utilizing obtained burned product after the decontamination as cement additives after ground and as construction materials consisting of this burned product, etc.
2. Description of the Related Art
A variety of proposals have been made on means and apparatus for decontaminating radioactive material from waste containing radioactive material such as radioactive cesium. For example, in the patent document 1 is disclosed a method of melting radioactive waste produced by nuclear fission that exists in a form of nitrate thorough electromagnetic induction heating in a cooling container with slits and a turning-on-electricity coil wounded on the outside of the container; volatilizing long-lived nuclides such as cesium; and separating and collecting the volatilized long-lived nuclides.    Japanese Patent Publication No. Heisei 5-157897 gazette
However, an issue that is produced in our country according to the accident of the nuclear power plant of this time and that should be solved is not carrying out decontamination of a waste generated by usual operation in nuclear related facilities, which is described in the above-mentioned patent document 1, but carrying out decontamination of radioactive materials that were emitted to the external world and incorporated into trees, soil, etc. Since attaining to a huge quantity of such radioactive waste is expected, it is especially important—to offer, not a proposal of a mere decontamination means, but a means for efficiently carrying out volatilization removal and collection of radioactive materials in large quantities to reduce costs for the processes.
If the waste containing radioactive materials is thrown and heated together with limestone into burning devices such as a kiln, it is possible to volatilize the radioactive materials and obtain a decontaminated product, but with conventional methods of heating waste only with burning devices as a kiln, energy for decarboxylation becomes necessary since limestone is mixed as it is, and it is expected that much energy is wasted. Then, when preheating devices such as a preheater were used and decarboxylation of limestone was performed to effectively use waste heat, radioactive cesium volatilized from a burning device became a solid; it returned to the burning device again; and circulation concentration was carried out, so that there was a possibility that a product, which should be decontaminated, might not certainly be decontaminated.
Therefore, this invention has been made in view of the above-mentioned problems to be solved, and the object thereof is to provide a method and an apparatus for certainly removing radioactive cesium from waste containing radioactive cesium with lower energy consumption.